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<div class="titlepage"><div><div><h3 class="title">
<a name="asio.reference.use_future_t"></a><a class="link" href="use_future_t.html" title="use_future_t">use_future_t</a>
</h3></div></div></div>
<p>
        Class used to specify that an asynchronous operation should return a future.
      </p>
<pre class="programlisting">template&lt;
    typename Allocator = std::allocator&lt;void&gt;&gt;
class use_future_t
</pre>
<h5>
<a name="asio.reference.use_future_t.h0"></a>
        <span><a name="asio.reference.use_future_t.types"></a></span><a class="link" href="use_future_t.html#asio.reference.use_future_t.types">Types</a>
      </h5>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
                <p>
                  Name
                </p>
              </th>
<th>
                <p>
                  Description
                </p>
              </th>
</tr></thead>
<tbody><tr>
<td>
                <p>
                  <a class="link" href="use_future_t/allocator_type.html" title="use_future_t::allocator_type"><span class="bold"><strong>allocator_type</strong></span></a>
                </p>
              </td>
<td>
                <p>
                  The allocator type. The allocator is used when constructing the
                  std::promise object for a given asynchronous operation.
                </p>
              </td>
</tr></tbody>
</table></div>
<h5>
<a name="asio.reference.use_future_t.h1"></a>
        <span><a name="asio.reference.use_future_t.member_functions"></a></span><a class="link" href="use_future_t.html#asio.reference.use_future_t.member_functions">Member
        Functions</a>
      </h5>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
                <p>
                  Name
                </p>
              </th>
<th>
                <p>
                  Description
                </p>
              </th>
</tr></thead>
<tbody>
<tr>
<td>
                <p>
                  <a class="link" href="use_future_t/get_allocator.html" title="use_future_t::get_allocator"><span class="bold"><strong>get_allocator</strong></span></a>
                </p>
              </td>
<td>
                <p>
                  Obtain allocator.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <a class="link" href="use_future_t/operator_lp__rp_.html" title="use_future_t::operator()"><span class="bold"><strong>operator()</strong></span></a>
                </p>
              </td>
<td>
                <p>
                  Wrap a function object in a packaged task.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <a class="link" href="use_future_t/operator_lb__rb_.html" title="use_future_t::operator[]"><span class="bold"><strong>operator[]</strong></span></a>
                </p>
              </td>
<td>
                <p>
                  (Deprecated: Use rebind().) Specify an alternate allocator.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <a class="link" href="use_future_t/rebind.html" title="use_future_t::rebind"><span class="bold"><strong>rebind</strong></span></a>
                </p>
              </td>
<td>
                <p>
                  Specify an alternate allocator.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <a class="link" href="use_future_t/use_future_t.html" title="use_future_t::use_future_t"><span class="bold"><strong>use_future_t</strong></span></a>
                </p>
              </td>
<td>
                <p>
                  Construct using default-constructed allocator. <br> <span class="silver"> &#8212;</span><br> Construct
                  using specified allocator.
                </p>
              </td>
</tr>
</tbody>
</table></div>
<p>
        The <a class="link" href="use_future_t.html" title="use_future_t"><code class="computeroutput">use_future_t</code></a>
        class is used to indicate that an asynchronous operation should return a
        std::future object. A <a class="link" href="use_future_t.html" title="use_future_t"><code class="computeroutput">use_future_t</code></a>
        object may be passed as a handler to an asynchronous operation, typically
        using the special value <code class="computeroutput">asio::use_future</code>. For example:
      </p>
<pre class="programlisting">std::future&lt;std::size_t&gt; my_future
  = my_socket.async_read_some(my_buffer, asio::use_future);
</pre>
<p>
        The initiating function (async_read_some in the above example) returns a
        future that will receive the result of the operation. If the operation completes
        with an <a class="link" href="error_code.html" title="error_code"><code class="computeroutput">error_code</code></a>
        indicating failure, it is converted into a <a class="link" href="system_error.html" title="system_error"><code class="computeroutput">system_error</code></a>
        and passed back to the caller via the future.
      </p>
<h5>
<a name="asio.reference.use_future_t.h2"></a>
        <span><a name="asio.reference.use_future_t.requirements"></a></span><a class="link" href="use_future_t.html#asio.reference.use_future_t.requirements">Requirements</a>
      </h5>
<p>
        <span class="emphasis"><em>Header: </em></span><code class="literal">asio/use_future.hpp</code>
      </p>
<p>
        <span class="emphasis"><em>Convenience header: </em></span><code class="literal">asio.hpp</code>
      </p>
</div>
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<td align="right"><div class="copyright-footer">Copyright &#169; 2003-2018 Christopher M. Kohlhoff<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
      </p>
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